A man can see distinctly from a distance of 0.5m. If he wants to read a book placed at a distance of 25cm, then what kind of lens should he use?
A person has near point of his vision shifted to 50 cm. What lens must be used to see an object placed at 25 cm from the eye? What is the power of the lens?
A person with defective eyesight is unable to see objects clearly nearer than 1.5 m. He wants to read a book placed at a distance of 30 cm from his eyes. The type of a required lens and its focal length is